public class Lv2Demo {
    public static void main(String[] args){
        YaJu yaJu = new YaJu();
        yaJu.showInfo();
        yaJu.speak();
        System.out.print("\n");
        Dog dog = new Dog();
        dog.showInfo();
        dog.speak();
        System.out.print("\n");
        Cat cat = new Cat();
        cat.showInfo();
        cat.speak();
        System.out.print("\n");
        Bird bird = new Bird();
        bird.showInfo();
        bird.speak();
    }

}
